Process of heat regeneration.



H. L. DOHERTY.

PROCESS OF HEAT REGENERATION.

APPLICATION FILED DEC.3I. I909'. RENEWED MAR. 21, 1913.

1,173,999. Patented Feb.29,1916.

2 'SHEETS-SHEET 1.

rr E I x 12 FIG. 1.

VAC V W Y o 420 co: HBI'HN Dohert y, avwowtoz a. (j I 7 83 220 @JctozmeqH. L. DOHERTY.

PROCESS OF HEAT REGENERATION. APPLICATION HLED DEC-3|, I909- RENEWEDMAR. 21. 1913- ZSHEETS-SHEET 2.

o 9 I Hen r8 L. Do hert y, gvwewtoz J QTMJZZJ alto mun TTE HENRY L.DOHERTY, OF NEW YORK, N. Y.

rnoo nss or HEAT Specification of Letters Patent.

rnaaao.

REGENERATION.

Patented Feb. 29, 1916.

Application filed December 31, 1909, Serial No. 535,841. Renewed March21, 1913. Serial No. 756,020.

T 0 all whom it may concern:

Be it known that I, HENRY L. DoHER'rY, a citizen of the United States,and a resident of New York city, in the county of New York and State ofNew York, have invented certain new. and useful Improvementsin Processesof Heat Regeneration, of which the following is .aspecification.

This invention relates to a process of heat regeneration, and, inparticular, to a process for securing heat regeneration in kilns for theburning of lime, brick kilns, billet reheating furnaces, etc., withspecial reference to its use in connection with the inventions which arethesubject of my Letters Patent No. 938,987, dated Nov. 2nd, 1909, andof my co-pending application Ser. No. 525,390, filed Oct. 29th, 1909.

In the accompanying drawings, I have illustrated the application of thispresent invention to the apparatus of the above mentioned Letters Patentand application for Letters Patent, and have, hereinafter, describedsuch application of my invention in detail. It is to be understood,however, that I do not limit this present invention to use in connectionwith the above mentioned inventions.

This invention is designed specially to be used in connection with theburning or heating of materials such as ordinary building brick, whichpossess a high thermal capacity but require in their burning a longflame of moderate temperature, and in particular in connection withtheheating of materials ac cording to the manner described in said patent.In the burning of such materials in this manner or in the ordinarymanner we are confronted with two interfering requirements. In bringingthe material up to the temperature of burning, even though the latter ismoderate-say 1600 to 1700 F.a large quantity of sensible heat is storedin the material. In order to recuperate this heat, it must be taken 'uby the air, or air and gas, supplied to com ustion zone of the kiln.Now, in such a case as we are considering, the quantity of. air requiredfor the combustion taking place, is much less than that which would benecessary to recuperate the sensible heat, which the bricks carry out ofthe combustion zone. If now we increase the quantity of air admitted tothe base of the kiln to that required to take up the heat of the bricksand return it to the combustion region, we must, in the ordinary way ofburning, have anexcess of air in the combustion zone. This causes thecombustion to take place with a sharp, intense flame, with a moderateexcess of air. The result is that the burning is very irregular. Thebricks in immediate contact with the flame are over-burned, while thosenot in contact with the flame are under-burned. The practical effect ofthis is, of course, a very ununiform product, with a large proportion ofrejects.

By my invention I can conduct the burning operatlon with just theproportion of air necessary to give the quality of flame that I desireand'yet am enabled to pass through the cooling chamber and preheatingchamber of the kiln the requisite quantity of air to insure thesubstantial recuperation of the sensible heat of the bricks. Iaccomplish this result in a kiln of the described type by introducinginto my kiln or burning chamber a by-pass consisting of a plurality ofoff-take ports below the gas-admission ports, corresponding inlet portsin the kiln walls well above the combustion zone, where the excess ofair will have no effect on my flame, and a suitable flue or fluesconnecting the OE-take and inlet ports. These ports and flues are madeof such size that the retardation exerted upon the air current passingthrough them by friction Will be practically negligible. When theapparatus is properly designed the resistance to the passage of the aircurrent is less in the by-pass flues than in the kiln shaft itself. Theresult, of course, is that a portion of the air current seeks this pathof least resistance and passes around the combustion zone of the kilnthrough the by-pass flues. The pro portion of the air, so passing, isregulated by the adjustment of the proper dampers located in the-by-passfiues. When the conditions are such that the draft through the by-passfines is not suflicient to overcome the draft of the stack itself I haverecourse to arrangement of a positive circulating device- (a fan or someequivalent device) interposed in the by-pass conduit to overcome thestack draft and draw ofi" the desired pro-.

portion of air below the combustion zone the same being returned to thestack above the combustion zone.

In the drawings, Figure 1 shows a vertical section through a kiln forburning bricks of the general type shown in my application for LettersPatent, -Ser. No.

525,390, modified for applying my present invention on the line C D ofFig. 2. Fig. 2 is a partial horizontal section through the battery onthe line A B of Fig. 1. Fig. 3 is a partial vertical section through oneof "the individual kilns on the line E F of and inlet ports. Fig. 6 is ahorizontal sec-Y tion through the line I J of Fig. 5; Fig. 7. is ahorizontal section through the line K L of Fig. 5; and Fig. 8 is ahorizontal section through the line M N of Fig. 5. Fig. 6 will alsoanswer'for a horizontal section on the line 0 P of Fig. 5 as they wouldappear the same, with the exception that the producergas conduit wouldnot be in section.

1, 1", etc., indicate the individual kilns of a battery. The method ofoperation is the same in all kilns, so I will restrict the followingdescription to kilns 1' and 1,

provided with natural and positive draft, respectively, in the airdiversion-Hues.

' 2 indicates the side-walls of kiln 1"; 3,

the end walls.

4 is the shaft of the kiln; 5, 5, etc., are ports for the admission ofair, having dampers 6.

7 refers to the cooler or lower part of shaft 4.

8, 8, etc., are air off-take ports; 9, 9, etc.,' are gas inlet ports;10, 10, etc., are vertical fiues built in the kiln walls, whose upperends communicate with the shaft of the kiln through the passages 11 andWhose lower ends communicate with the ports 8.

12 are dampers regulating the draft through the flues 10 which areaccessible through the hand-holes 13,-having covers 14;. '15 indicatesthe combustion zone of the kiln; 16 are auxiliary air portscommunieating with fiues '10, access to which is had through hand-holes17 through which the laterally-movable, dampers 18 maybe adjusted. r

19, 19,etc., are ports for drawing off aportion of the combustion gasesunder the action of an injector or fan. These combustion gases are thensupplied to the fuel bed of the gas producer 20. In contact with the hotfuel in 20, a portion of the CO parts with one-half of its oxygen to thecarbon to generate carbon monoxidan equal volume of the same gas bein atthe same time formed by the reduced C This reaction,

which is a highly endothermic one, absorbsv that portion of the sensibleheat which the of the fuel bed. At the same time, for agiven amount ofcombustible gas required, this circulation of a portion of the hotcombustion gases from the combustion zone, permits of a reduction to theminimum of the atmospheric air required in the gas producer, and thuscorrespondingly reduces the heat drain on the system and permits oftheheating of the bulk of the air required by the system. by heat recoveredfrom the burned material. Only the relatively small quantity of airrequired to supplement the heat carried by the combustion gases in orderto maintain the fuel bed of the producerat a reactive temperature issuppliedto the same. Since, as stated in the application referred to, Ipass the draft current of combustion gases through the producer un-- derconditions such that only a portion of their CO is dissociated, thecombustible gas producedis diluted with a comparatively considerableproportion of noncombustible gases. This modified producer gas passes tothe kiln through the conduits shown and is introduced into the lowerportion of the combustion zone 15 through the ports 9. In

15 the gas is burned by that portion of the air which is permitted toascend into 15 from the cooler 7, with the production ofa dilated frame.of moderate temperature,

'which enables me to secure an active circulation of the flame aroundand in contact with circul'ationof application 525,390 andthe aircirculation herein disclosed I have devised an improved process of heatrecuperation which permits of the securing of a greater heat economy, inthe operation of apparatus of the type referred to, than is possible bythe methods of operation at present known to the art.

As the combustion gas circul'atio'n,in the embodiment of my invention asapplied to the operation of a kiln as an improvement upon the process ofmy Letters Patent No; 938,987, above referred to, is substantially thesameas described above, no further detailed description of the same isnecessary.

In the t pe of kiln 1", shown in Figs. 5 to 8, provi 21 refers to thatportion of the kiln shaft lwhich I designate as the pre-heating cham- 22indicates a draft-producing means, discharging into a conduit 23.

ed with forced circulation of air,

When the kiln is in normal operating conditionthe shaft 4: is filledwith bricks, lime- Y connecting flues 10, in the kiln walls, and

returns to the shaft through the ports 11. The proportion of air passingthrough the flues 10 is regulated by adjusting the dam- I pers 12through the hand-holes, 13, which are ordinarily closed by covers 14.Theproportion of air' by-passed around the combustion zone, 15, throughthe by-pass flues seldom exceeds one-half of the total volume of airentering the bottom of the kiln,

, although I do not restrict myself-to the bypassing of any specificproportion since the proportion so by-passed will, of course, dependupon the requirements of each particular case. Usually, I permit to passup through the stack to the combustion zone just about the theoreticalquantity of air for the complete combustion of the gas introducedthrough 9. Under some conditions, however, I'may restrict this" portionof the air to less than this quantity, introducing the balance of theair required, to make up this quantity, through auxiliaryports 16,connected with flues 10. Suitable hand-holes 17, provide access to 16,and permit of the adjustment of the laterallymovable dampers 18, toregulate the volume of air passing through 16 to the proper quantity. Bythis device, I produce a long, slow burning flame of moderatetemperature, in which the combustion is not completed, until it hasreached a level in the shaft above the auxiliary ports 16. s Thequantity of air by-passed is fixed by (a) the quantity of air necessaryto cool the burned bricks (or. other material) and (b) the quantitywhich is required in the combustion zone proper. It is the differencebetween the quantities (a) and (b) which I withdraw through 8 and bypassaround the region 15. The ports, 11, are located, preferably, at the.height in the kiln at which the combustion gases from the region 15will, in normal running, have substantially the same temperature. as theby-Oassed air. "W hen, however, as in the particular application of myinvention, which we are considering, a portion of the combustion gasesare withdrawn from the kiln for use in regulating the thermic conditionsin the producer, it is desirable to locate the ports 11 above thecombustion gas off-takes 19, thus avoiding the dilution of thecombustion gases going to the producer 20.

The by-passed air mingles with the currentof combustion gases in what Idesignate as the preheating region, 21, of my kiln and yields up itsheat to the descending unburned material in the region 21. The netresult of my process is, therefore, to take up from the finishedmaterial that portion of the sensible heat which it carries which thenormal quantity of combustion a1r cannot take up and to transfer thisheat to the descending raw material in the preheating region 21. Thus,no matter What the heat capacity of the material passing through thekiln may be, I am able to eifect substantially perfect recuperation ofthe heat which it carries and at the same time conduct my combustionwith just the proper quantity of air to secure the conditions which 1desire in the combustion region 15. When, as may sometimes happen in theburning of limestone, where the material is in fragments of large sizeand comparatively large passageways are automatically formed in thecharge for the passage of the combustion gases, there may not be asufficient difference in the draft through the by-pass flues and thestack itself to divert the desired proportion of the air through theby-pass flues, I interpose a positive draft-producing device, 22, in theit up outside the kiln. The method of operation is, however, identicalwith that of the apparatus, just described.

Having described my invention, what I claim is 1. In connection withtheoperation of a heating or calcining chamber, the process of heatregeneration which consists'in passing in contact with the heatedmaterial from the combustion zone of said chamber, a current of air, thevolume of the said air being suflicient to take up,substantially, all ofthe sensible heat of the said heated material, whereby the saidheated'material is cooled and the said air-current heated, dividing theso-heated air current into two streams, at a place in said' chamberadjacent to the combustion zone thereof, passing one of said air streamsinto the said combustion zone, the

volume of said air-stream being less than I that required to support thecombustion taking place in the said combustion zone, conducting theother of said air-streams around the said combustion zone. subdividingthe other of said air-streams into a major and a minor portion anduniting said major portion with the products of combus tion from thesaid combustion zone, introducing the said minor portion into an.intermediate region of said combustion zone to complete combustiontherein, and passing the commingled stream of heated air and products ofcombustion in contact with the relatively cold unheated materialapproaching the combustion zone, whereby the saidunheated material isheated and the said stream of heated air and products of combustioncooled.

2. In the operation of a heating or calcining chamber, the process ofheat regeneration, which consists in transferring part of the, heat ofthe heated material leaving the combustion zone of said chamber,'to therelatively-cool material approaching the combustion zone of saidchamber, by means of a current of-air as a vehicle, and transferringanother part of the sensible heat of the heated material to thecombustion zone of said chamber by means of the air supplied tosaidcombustion zone as a vehicle, and re passing a portion ot the combustiongases generated in said combustion zone through a comparatively deep bedof incandescent tuel and back to said zone.

3. The processof heat regeneration which comprises passing air incontact with the heated material in. a heating chamber,

whereby the said air is heated by the sensible heat of said material,the Volume of said air being in excess of that required for thecombustion in said chamber, dividing said air current into two streams,passing one of said streams into the combustion zone of said chamber,by-passing' the other of cooled, dividing the so-heated air current intotwo main streams, passing thefirst of said streams into the saidcombustion zone, at that region of the same Wherethe required fuel isintroduced thereinto subdividing the second'of said'main streams into amajor and a minor portion, introducing the said minor portion of saidsecond stream into a mid region of said combustion zone, conducting thesaid major portion of said second air stream around the said combustionzone, uniting it with the products of combustion from the saidcombustion zone, and passing the commingled streams of body of materialpassing through a zone of combustion, passing air in'heat-absorbingrelationship to the hot material passing be-.

yond the zone of combustion, transmitting a portionzof the air so heatedto said zone to maintain combustion therein, diverting the residue ofair so heated around the zone of combustion, passing a portion of saiddiverted air into contact with the material advancing toward said zone,and repassing through said zone of combustion a portion 7 of thecombustion gases leaving the same.

6. The process of regenerating heat which comprises providing a movingor traveling body of material passing through a zone of combustion,passing air in heat-absorbing relationship to the hot material passingbeyond the zone of combustion, transmitting a portion of the air soheated to said zone to maintain combustion of combustible gas therein,diverting the residue of the air so heated around the zone ofcombustion, passing an admixture of said diverted air with a firstportion of the products of combustion into coiitact with the materialadvancing toward said zone, diverting a second portion of said productsof combustion, contacting said diverted portion of products ofcombustion with incandescent carbon to generate combustible gas, andintroducing said combustible gas into said combustion zone.

7. The process of regenerating heat which comprises providing a moving'or traveling body of material passing through a zone of combustion,passing air in heat-absorbing relationship to the hot material passingbe yond thezone of combustion, transmitting a portion of the air soheated to said zone to maintain combustion therein, diverting theresidue of the air so heated around the zone of combustion, passing anadmixture of said diverted air with a first portion of the hot productsof combustion leaving said combustion zone into contact with thematerial, and repassing a second portion of said products of combustionthrough said combustion zone to increasethe velocity of flow of gasestherethrough.

8. The process of regenerating heat which comprises providing a movingor traveling body of material passing through a zone of combustion,passing air in heat-absorbing relationship to the hot material passingbeyond the zone of combustion, transmitting a portion of the air soheated to said zone to maintain combustion therein, diverting theresidue of the air so heated around the masses zone of combustion,passing an admixture of a portionofsaid diverted air with a firstportion of the products of combustion leaving said zone of combustioninto contact with the material advancing toward said zone,-the admixturebeing at a point where the temperature of said products is substantiallythe same as that of said air, introducing another portion of saiddiverted air into an intermediate region of said combustion zone,diverting a second portion of said products of combustion, contactingsaid second portion with carbon to change a portion of said products ofcombustion to combustible gas, and introducing the said products ofcombustion, after they have been contacted with carbon, into said zoneof combustion.

9. The process of heating and heat regeneration which comprisesadvancing material to be heated to, through and beyond a zone ofcombustion, cooling the hot material and heating air beyond said zone bya sufiicient supply of ontacting air, transmitting a limited amount ofthe air thus heated into said zone to aid and maintain combustiontherein, by-passing another portion of the heated zone heating thematerial by combustion in the presence of a limited amount of heatedair, increasing the velocity of flow of the products of said combustionthrough said zone by maintaining a circulation of an excess ofcombustion gases from the discharge end to the fuel admissionend of saidzone, contacting the hot material in its passage beyond said zone with arelatively large amount of air, introducing a regulated amount of theair thus heated into said combustion zone to support said combustion,and by-passing another portion of said heated air around said combustionzone to form said admixture.

11. The process of heat regeneration which comprises advancing materialto be heated to, through and beyond a zone of combustion, and in itsprogress toward said zone heating the material by contacting with anadmixture of'heated air and products of combustion, in its progressthrough said zone heating the material by a long comparativelycool flameof gas burning in the presence of a limited amount of heated air,

the velocity of flow of the gases from said flame being increased by theaddition thereto of combustion gases previously discharged from saidzone of combustion, contacting the hot material in its passage beyondsaid zone with a relatively large amount of air to heat said air,introducing a regulated portion of the air thus heated into saidcombustion zone to support said combustion, and by-passing anotherportion of said heated air around said combustion zone to form saidadmixture.

Signed at New York city inthe county of New York and State of New Yorkthis 30th day of December A. D. 1909,

HENRY L. DGHERTL Witnesses:

7. J. QUENTIN, THos. ll. CARTER,

